<!DOCTYPE html>
<html lang="en">
<head>
  <meta charset="UTF-8">
  <meta name="viewport" content="width=device-width, initial-scale=1.0">
  <meta http-equiv="X-UA-Compatible" content="ie=edge">
  <title>promise的几个关键问题1</title>
</head>
<body>
  <script>
    /* 
    1.	如何改变promise的状态?
      (1)resolve(value): 如果当前是pendding就会变为resolved
      (2)reject(reason): 如果当前是pendding就会变为rejected
      (3)抛出异常: 如果当前是pendding就会变为rejected
    
    2.	一个promise指定多个成功/失败回调函数, 都会调用吗?
      当promise改变为对应状态时都会调用
    */

    const p = new Promise((resolve, reject) => {
      // resolve(1) // promise变为resolved成功状态
      // reject(2) // promise变为rejected失败状态
      // throw new Error('出错了') // 抛出异常, promse变为rejected失败状态, reason为 抛出的error
      throw 3 // 抛出异常, promse变为rejected失败状态, reason为 抛出的3
    })
    p.then(
      value => {},
      reason => {console.log('reason', reason)}
    )
    p.then(
      value => {},
      reason => {console.log('reason2', reason)}
    )

    
  </script>
</body>
</html>